Union City is located in Alameda County on the east side of the San Francisco Bay. Encompassing 18 square miles (nearly 11,500 acres), Union City lies between the city of Hayward to the north and west, the city of Fremont on the south and east, and salt marshes on the west. Farmers in this area, with its fertile soil, marshes, and proximity to San Francisco, were able to easily exploit these resources.

The largest producer of rhubarb in the United States, Union City also ranked as the highest producer of mushrooms and currants in California. Peas, potatoes, string beans, sweet corn, spinach, cabbage, carrots, hay barley, wheat and oats were also grown in the area. Alvarado was known for salt harvesting, as well as the first and largest production of sugar from sugar beets.

The first people in Union City were the Costanoan Indians who lived in villages along two major watercourses, Alameda and Dry Creeks.

In 1836, the town of Alvarado, named after the Mexican governor, John B. Alvarado, was one of the early settlements in southern Alameda County. Alvarado grew around Alameda Creek and was laid out in a traditional gridiron pattern. During the early 1850s the town included a tavern, store, two warehouses and several homes.

In 1850, John Horner, with his brother William, shipped crops netting almost $100,000 and laid out a town eight blocks square. He purchased a small Sacramento River steamer called The Union and named his settlement Union City. He started a general store.

The steamer, captained by Captain Marsten, made the round trip to San Francisco once a day with produce and brought back passengers, mail, hardware, tools and merchandize.

Henry Smith, a storekeeper and American Alcalde in Mission San Jose, sold his store and moved to Union City near John Horner. Smith built two warehouses at the wharf in Union City. He started a settlement called New Haven, named for his hometown in Connecticut. It was north and east of the great elbow of the creek. Hotels and eating establishments sprang up along with saloons and gaming rooms.

In 1853, New Haven (Alvarado) was made the first County Seat.

A.W. Church arrived in California from New York in l849. After failing as a miner, he opened the first store in New Haven (Alvarado). In 1853, he was elected as the first County Clerk of Alameda. His store became the first County Courthouse.

In 1870, Ebenezer H. Dyer, along with his brother Ephraim, bought a beet sugar factory, which was built on his property, the first such successful operation in the United States.

Landlocked, Decoto became a railroad town whose growth was spurred by the arrival of the Western Pacific Railroad through Niles Canyon in l869. The town was formed out of land owned by the family of Ezra Decoto, whose name street and area memorialize names around town.

John C. Whipple was lured to California in search of gold in the spring of l854. He bought 200 acres near the Decoto Brothers Ranch on what is now Whipple Road. He added more to his domain on the hills, east of the Hayward-Niles Road. He planted fruit trees and used the land for cattle, as well as the raising of grains and vegetables.

John Quigley was a pioneer in the salt industry. As early as l850, in New Haven (Alvarado), salt deposits were gathered, and for a long time all of Alameda County depended on the supply.

The Cheng family farmed acres and acres of land in Union City. The Wah Sing Cheng Farm was located at the site where the Crown Plaza at Alvarado-Niles Road is located now.

Union City was incorporated in 1959 as an agricultural town of dirt roads, very few homes and residents, cauliflower and cabbages.

As the population began to increase, new homes appeared in the area. The Union City vision was for a friendly community with green open space, beautiful neighborhood, and great shopping centers, commercial and industrial development. Today, that vision has become reality and Union City's unique personality, strengths, dreams and successes have come to fruition as the city is one of the fastest growing communities in the area.